JP2019199809A - Engine with blow-by gas recirculation device - Google Patents

Abstract

To provide an engine with a blow-by gas recirculation device which is improved not to cause inconveniences due to freezing at a low temperature by devising its construction so that a blow-by gas passage is hardly frozen at its terminal end connected to an intake system.SOLUTION: The engine with the blow-by gas recirculation device is constructed to guide blow-by gas from a crank case through the inside of a head cover 3 into an intake system k. The intake system k has a cover intake passage 19A provided in the head cover 3. A blow-by gas passage 26 of the head cover 3 and the cover intake passage 19A are communicated with each other. In a bottom wall 25 of the blow-by gas passage 26, a return hole 33a is provided where oil trapped in the blow-by gas passage 26 can drop. On the bottom wall 25 at a portion around the return hole 33a, a downward inclined surface 32 is formed which is gradually lower as extending to the return hole 33a.SELECTED DRAWING: Figure 7

Description

  The present invention relates to an engine with a blow-by gas recirculation device such as an industrial engine and a traveling vehicle engine.

  The engine is equipped with a mechanism that recirculates the blow-by gas that accumulates in the crankcase to the intake system such as the air intake passage, mixes it with new air-fuel mixture, burns it, and does not release it as it is, that is, the blow-by gas recirculation device Is provided. In an engine with a blow-by gas recirculation device, it is desirable to remove liquid components such as oil (oil mist) and water contained in the blow-by gas as much as possible before returning them to the intake passage.

  Therefore, conventionally, a configuration is often adopted in which the liquid component is returned from the crankcase to the intake system through the cylinder head and the head cover so that the liquid component is easily captured inside the engine. As such an example, one disclosed in Patent Document 1 is known.

JP 2008-163837 A

  Generally, the piping that returns the blow-by gas to the intake system is exposed to the outside of the engine and therefore tends to be vulnerable to cold. Under extremely low temperature conditions, blow-by gas returning to the intake passage is cooled by fresh air in the intake passage, and moisture in the blow-by gas is frozen at the outlet of the pipe, which may cause clogging.

  An object of the present invention is to connect the blow-by gas in the crankcase to the intake system in the blow-by gas passage by structural modification in an engine with a blow-by gas recirculation device configured to guide the blow-by gas in the crankcase through the inside of the head cover to the intake system. Therefore, it is possible to provide an engine with a blow-by gas recirculation device which is improved in such a manner that the inconvenience caused by freezing at a low temperature does not occur as much as possible.

In the present invention, a cover intake passage that is a part of an intake system that sends air to the intake manifold is integrally attached to the head cover, and the blow-by gas passage and the cover intake passage of the head cover are communicated with each other.
The bottom wall of the blow-by gas passage is provided with a return hole for dropping captured oil and a downwardly inclined surface formed in the peripheral portion of the return hole in a state where the height decreases toward the return hole. It is characterized by.
For example, the blow-by gas outlet portion is formed below the cover intake passage in the head cover, and the above-described return hole and the downward inclined surface are formed on the bottom wall of the blow-by gas outlet portion.

The head cover is a portion where heat is transferred from the cylinder head and warms, and blow-by gas is returned to the cover intake passage which is a part of the warmed head cover. Therefore, even if the intake air is cold due to extreme cold or the like, the temperature of the air flowing through the cover intake passage rises, so that the water in the blow-by gas recirculated to the middle portion of the passage is eliminated or suppressed. Become.
In addition, since the bottom wall of the blow-by gas passage is provided with a return hole and a downwardly inclined surface that becomes lower toward the return hole, the oil flows naturally by gravity even if the engine is slightly inclined. In addition, there is an advantage that the action of collecting the trapped oil to the return hole by the downward inclined surface is promoted.

  As a result, an engine with a blow-by gas recirculation device that has been improved so that the inconvenience caused by freezing at low temperatures is minimized as a result of structural innovations that makes it difficult to freeze at the end portion connected to the intake system in the blow-by gas passage. Even if the engine is slightly inclined, the oil in the blow-by gas can be provided in a preferable state in which the oil is favorably reduced from the return hole into the engine.

Left side view of industrial diesel engine Front view of the engine shown in FIG. 1 is a right side view of the engine shown in FIG. Plan view of the engine shown in FIG. Rear view of the engine shown in FIG. Top view around the front of the head cover Left side view of the cutout showing the head cover and cover intake passage Top view of the head cover Bottom view of head cover FIG. 8 is a front view of the head cover and a partly cutaway portion according to the cross-sectional view taken along the line XX of FIG. (A) Top view of gas outlet cover showing cover intake passage, (B) Bottom view of gas outlet cover showing cover intake passage The relationship between the blow-by gas outlet and the valve gear is shown, (A) is a cross-sectional view, and (B) is a longitudinal cross-sectional view of the main part. (A) Side view of discharge reed valve, (B) Side view of return reed valve (A) Plan view of gasket, (B) Cross section of gasket and upper and lower parts thereof Bottom view showing valve body with rubber coated tip

  Hereinafter, an embodiment of an engine with a blow-by gas recirculation device according to the present invention will be described with reference to the drawings when applied to an industrial diesel engine.

  As shown in FIGS. 1 to 5, an industrial diesel engine (hereinafter simply referred to as an engine) E has a cylinder head 2 assembled on the upper part of a cylinder block 1 and a head cover 3 on the upper part of the cylinder head 2. The oil pan 4 is assembled to the lower part of the cylinder block 1. A transmission case 5 is assembled at the front end of the cylinder block 1, an engine cooling fan 6 is disposed at the front of the transmission case 5, and a flywheel 7 is disposed at the rear of the cylinder block 1. The upper half part of the cylinder block 1 is constituted by a cylinder 1A, and the lower half part is constituted by a crankcase 1B.

  At the front of the engine E, a driving pulley 8 attached to the shaft end of a crankshaft (not shown), a driving fan pulley 6A for the engine cooling fan 6, and a transmission belt 10 straddling a passive pulley 9A for a dynamo (alternator) 9; A water flange 21 and the like are provided. On the left side of the engine E, an exhaust manifold 11, a supercharger 12, a starter 13, an oil filter 14 and the like are provided. An intake manifold 15, a fuel injection pump housing 16, a stop solenoid 17 and the like are provided on the right side of the engine E, and three injectors 18, a compressor upstream suction passage 19, a compressor downstream suction passage 20, and the like are disposed above. Yes.

  The compressor downstream side intake passage 20 includes a start end side pipe 20A connected to the compressor housing 12A and disposed just above the head cover 3, and a terminal end side pipe 20B connecting the start end side pipe 20A and the intake manifold 15. Configured. As shown in FIG. 4, the start end side pipe 20 </ b> A is arranged in a state along the position on the rear side of the cover intake passage 19 </ b> A in plan view. The bent pipe 19B, the start side pipe 20A, and the end side pipe 20B may be made of a pipe made of a material having flexibility such as rubber, or a metal pipe.

  As shown in FIGS. 4, 6, 7, and 10, the engine E has a blow-by gas recirculation configured to guide the blow-by gas in the crankcase 1 </ b> B through the inside of the head cover 3 to the intake system k. Device A is equipped. The head cover 3 is a bottomless box-like (upper lid-like) part that is assembled to the cylinder head 2 across the valve gear B, and a plurality of ribs 3a extending in the left and right directions are formed inside the cover. An engine oil supply hole 22 is provided in the rear portion of the head cover 3.

  The intake system k has a cover intake passage 19A provided in the blow-by gas outlet portion 3A of the head cover 3, and the blow-by gas passage 26 and the cover intake passage 19A of the blow-by gas outlet portion 3A communicate with each other. The cover intake passage 19A is configured as a part of a compressor upstream intake passage (an example of an intake passage) 19 that connects the air cleaner 23 (see FIGS. 4 and 6) and the supercharger 12. In other words, the compressor upstream suction passage 19 includes a cover intake passage 19A, and a bent pipe 19B that connects the cover intake passage 19A and the compressor housing 12A of the supercharger 12. Note that the intake system k is a concept such as an air cleaner 23 and an intake manifold 15 that are all passages for sending air a to a combustion chamber (not shown).

  Here, the main function in the blow-by gas recirculation apparatus A (recirculation part to the intake system k) will be briefly described. As shown in FIGS. 6 and 7, the blow-by gas g flowing from the cylinder block 1 to the inner space of the head cover 3 passes through a discharge reed valve (an example of a discharge check valve) 31 and is discharged from the blow-by gas outlet 3 </ b> A. It enters the space part 26 which is a blow-by gas passage. The blow-by gas g that has entered the space 26, also called a CCV (crankcase ventilation) chamber, passes through the communication hole 38 of the gasket 35 and is returned to the cover intake passage 19 </ b> A, that is, to the intake system k.

Next, the head cover 3 and the cover intake passage 19A will be described in detail.
As shown in FIGS. 6 to 10, the head cover 3 having a rounded quadrangle (oval) in plan view has a blow-by gas outlet 3 </ b> A that is open upward at the front end of the top wall 3 </ b> C. . The blow-by gas outlet 3 </ b> A is formed in the head cover 3 as a coverless box-shaped portion including a space 26 surrounded by a vertically-facing partition wall 24 and a bottom wall 25 and a joint surface 27 that is an upper surface.

  The space part 26 which is a blow-by gas passage is a part exhibiting a trapezoidal shape with a short side on the right side in a plan view, and the bottom wall 25 is different from the shallow main bottom surface 25A in a state where the depth differs in the front-rear direction. It has sink bottom surfaces 25B and 25B formed respectively before and after the bottom surface 25A. A discharge reed valve 31 for sending the blowby gas g from the inside of the head cover 3 is provided in a lateral (leftward) posture at the front and rear central portion of the main bottom surface 25A that exhibits a lateral T-shape in plan view.

  As shown in FIGS. 7 to 10, 12, and 13, the discharge reed valve 31 includes a thin discharge valve body 31 </ b> A disposed on the main bottom surface 25 </ b> A and a thick discharge valve guide 31 </ b> B, respectively. It is comprised by bolting to the bottom wall 25 in the base side. A round tip 31a of the discharge valve body 31A is disposed on the upper side of the discharge valve hole 31C formed in the bottom wall 25 so as to open to the main bottom surface 25A, and normally serves as a lid of the discharge valve hole 31C (valve closing). Status). The portion of the discharge valve hole 31C in the bottom wall 25 is formed in a protruding hole wall 25a that has a round shape concentric with the discharge valve hole 31C when viewed in the vertical direction and protrudes downward. In the discharge reed valve 31, the main bottom surface 25 </ b> A functions as a valve seat 25 </ b> A that comes into contact with the tip portion 31 a.

  The sink bottom surface 25B includes a downwardly inclined surface 32 that becomes lower from the front and rear of the discharge reed valve 31 toward the front and rear, and a lowest surface 33 that continues to the lower side of the downwardly inclined surface 32 (see FIG. 8). The lowest surface 33 is configured to be located closer to the left side with respect to the descending inclined surface 32. Each bottom surface 33, 33 in the bottom wall 25 is formed with a return valve hole (an example of a return hole) 33a penetrating vertically, and a return lead valve (an example of a return check valve) 34 for the return valve hole 33a. Is provided.

  That is, the bottom wall 25 of the space portion 26 is provided with a return valve hole 33a capable of dropping the oil trapped from the blow-by gas g in the space portion 26, and in the peripheral portion of the bottom wall 25 around the return valve hole 33a, A downwardly inclined surface 32 is formed that decreases in height toward the return valve hole 33a. Each return valve hole 33a is formed so as to open to the lowest surface 33 having a height lower than that of the main bottom surface 25A.

  As shown in FIGS. 7 to 10, 12, and 13, the return reed valve 34 includes a return valve body 34 </ b> A that is in contact with the opposite side of the lowest surface 33, i.e., the lowest back surface 33 </ b> A, on the bottom wall 25. The valve guide 34B is configured by bolting to the bottom wall 25 on the respective base sides. The return reed valve 34 is provided upside down with respect to the discharge reed valve 31. Normally, the return valve hole 33a is lightly closed by the tip 34a of the return valve body 34A, or the return valve body 34A is It is in a very slightly open state due to a slight sagging displacement. The return reed valve 34 functions as a valve seat 33A in which the lowest back surface 33A comes into contact with the tip end portion 34a.

  Each of the return reed valves 34, 34 is disposed in a lateral orientation in which the tip 34a of the return valve body 34A is on the left side, and returns the oil trapped from oil mist or the like contained in the blow-by gas g in the space 26. It is a valve which acts on the valve hole 33a. The diameter of each return valve hole 33a is smaller than the diameter of the discharge valve hole 31C. The discharge valve body 31A and the return valve body 34A, and the discharge valve guide 31B and the return valve guide 34B are convenient if they are the same parts, but may be different. As shown in FIGS. 8 and 9, a pair of return reed valves 34 are provided on the front and rear sides of the discharge reed valve 31.

  As shown in FIG. 6 to FIG. 8 and FIG. 11, a gas outlet cover 3B is bolted on the blow-by gas outlet portion 3A, and the gas outlet cover 3B includes a lid cover portion 36, a cover intake passage 19A, It is configured with. The lid cover part 36 has the same outer shape as the blow-by gas outlet part 3A in plan view, and is a part that is fixed to the head cover 3 by bolting at three places with the gasket 35 interposed therebetween.

  As shown in FIG. 11, the cover intake passage 19 </ b> A is meandering so that the passage end portion 19 b of the cover intake passage 19 </ b> A is inclined outward in the longitudinal direction of the head cover 3 with respect to the passage start end portion 19 a of the cover intake passage 19 </ b> A. It is formed in the passage. Specifically, the cover intake passage 19A extends in a direction orthogonal to the head cover longitudinal direction (front-rear direction) (an example of intersection) and is parallel to each other, a passage start end portion 19a and a passage end portion 19b, and a passage start end portion 19a end and passage. It is formed in a serpentine passage having a crank shape (substantially Z shape) in a plan view, having a passage intermediate portion 19c that is inclined in the front, rear, left, and right directions connecting the starting end of the end portion 19b.

  The passage middle portion 19c is formed in a groove-like passage portion having a downward U-shaped cross section, and the opening 37 at the lower end of the passage intermediate portion 19c has a shape similar to that of the groove-like passage portion 19c and opens downward. Is formed. Further, the lid cover portion 36 is formed with a lightening portion 36a that is located behind the opening 37 and opens downward, and has three bolt holes 3b. As shown in FIG. 11B, the lower end of the lid cover portion 36 is formed on a substantially “day” -shaped joining lower surface 36b.

  As shown in FIG. 14A, the gasket 35 has a thin plate shape (sheet shape) provided with one communication hole 38 and three bolt insertion holes 39. As shown in FIG. 14B, the gasket 35 is sandwiched between the joint surface 27 that is the upper surface of the blow-by gas outlet portion 3A and the joint lower surface 36b (of the gas outlet cover 3B) of the lid cover portion 36. It is provided in the state. The outer shape of the joint surface 27 of the blow-by gas outlet portion 3A, the outer shape of the gasket 35, and the outer shape of the lid cover portion 36 are the same.

  As shown in FIG. 6, the space portion 26 of the blow-by gas outlet portion 3 </ b> A has an upper surface opening that covers almost the entire surface of the opening 37 of the lid cover portion 36, and the communication hole 38 of the gasket 35 is a space portion. 26 and the only opening 37 that communicates with the opening 37. That is, the communication hole 38 is set as a hole that defines a communication area between the passage intermediate portion 19c (opening opening 37) and the space portion 26 and a communication position with respect to the passage intermediate portion 19c. It can be said that the communication hole 38 defines a communication position with respect to the space portion 26. The communication hole 38 is a circular hole, but various shapes such as an ellipse and a square can be set.

  The valve gear B will be briefly described. As shown in FIGS. 8, 10, and 12, the valve operating apparatus B includes a rocker arm shaft 28 that extends in the front-rear direction and is supported by a plurality of portions of a shaft support portion 2 a that is erected on the cylinder head 2. A plurality of (six in total) rocker arms 29 and 30 are provided for supply and exhaust, which are pivotally supported by the arm shaft 28.

  The rocker arms 29 and 30 are provided with drive side end portions 29a and 30a for operating supply / discharge valves (not shown) and passive side end portions 29b and 30b driven by push rods (not shown). The cylinder head 2 is formed with a push rod hole (not shown) that is formed to allow the push rod to pass therethrough. As shown in FIG. 8, the blow-by gas g passes through the push rod hole in the head cover 3. Will be sent to.

  As shown in FIG. 12 (B), the position where the valve gear B and the bottom wall 25 come closest is the back surface of the rocker arm 29, the second rocker arm 30 from the front, and the descending inclined surface 32. It is between the upper and lower sides with a certain inclined back surface 32a. More specifically, as shown in FIG. 12 (A), between the upper and lower passive side end portions 29b, 30b and the corresponding inclined back surfaces 32a, there is a sufficient gap even at the closest point, That is, the clearance c (example: 3 mm) is set.

  In the blow-by gas recirculation device A, the interior of the head cover 3 and the space 26 are partitioned by a bottom wall 25 having a discharge reed valve 31 and two return reed valves 34, 34. Is communicated with the cover intake passage 19 </ b> A through the communication hole 38 of the gasket 35. Therefore, when the internal pressure of the head cover 3 is higher than the pressure of the cover intake passage 19A, the discharge reed valve 31 is opened, and the blow-by gas g in the head cover 3 passes through the discharge reed valve 31, the space 26, and the communication hole 38. It enters the passage middle portion 19c and is returned to the intake system k.

  When the internal pressure of the head cover 3 and the pressure of the cover intake passage 19A are the same, or when the internal pressure of the head cover 3 is lower than the pressure of the cover intake passage 19A, the pair of return reed valves 34 and 34 are opened. When the return reed valve 34 is opened, oil (engine oil) captured from the blow-by gas g in the space 26 is dropped into the head cover 3 (below the bottom wall 25) from the front and rear return valve holes 33a and 33a. It is. The oil falling from the return valve hole 33a is not only returned to the inside of the engine, but also as shown in FIG. 12 (b), such as a sliding portion (not shown) between the rocker arm shaft 28 and the rocker arm 29, etc. A good lubrication function supplied to the device B is also obtained.

  In the engine with a blow-by gas recirculation device according to the present invention, a cover intake passage 19A, which is a part of the compressor upstream suction passage 19, is attached to the head cover 3, and the blow-by gas passage 26 of the blow-by gas outlet 3A and the cover intake passage 19A The passage intermediate portion 19 c communicates with the gasket 35 through the communication hole 38. The head cover 3 is a portion that is warmed by heat conduction from the cylinder head 2, and the blow-by gas g is returned to the cover intake passage 19 </ b> A that is a part of the warmed head cover 3.

  Accordingly, even if the intake air a is cold due to extreme cold or the like, the temperature of the air a flowing through the cover intake passage 19A is increased (see FIG. 11A), so that the blow-by gas g returned to the passage intermediate portion 19c The freezing of water in the water is eliminated or suppressed. As a result, it is possible to provide an engine with a blow-by gas recirculation device that is improved in such a way that it becomes difficult to freeze at the end portion connected to the intake system of the blow-by gas passage 26 and inconvenience due to freezing at low temperatures does not occur as much as possible. .

Since the downward inclined surface 32 whose height decreases toward the return valve hole 33a is formed in the peripheral portion of the return valve hole 33a, the action of collecting the captured oil in the return valve hole 33a is promoted. There is an advantage that the oil flows into the return valve hole 33a even if the engine is slightly inclined.
Since the return reed valve 34 for the return valve hole 33a is provided, there is an advantage that the captured oil can be dropped while preventing the blow-by gas g from flowing into the space portion 26 from the return valve hole 33a. .

Since the valve operating device B is arranged below the return valve hole 33a, the oil supplied to the sliding portion between the rocker arm 29 and the rocker arm shaft 28 is supplied by the oil dropped from the return valve hole 33a. There is also an advantage that can be done.
Since the return reed valves 34 and 34 are arranged on the front and rear sides of the discharge reed valve 31, the oil can smoothly flow into any of the return valve holes 33 a regardless of whether the former leans forward or backward. It is.

[Another embodiment]
As shown in FIG. 15, a thin film made of rubber (an example of an elastic material) 40, ie, a rubber sheet, is formed on the tip 34a of the return valve body 34A of the return reed valve 34 on the surface that comes into contact with the valve seat 33A. It is advantageous if the (rubber film) 40 is coated. There exists an advantage which can contribute to the improvement of the sealing performance at the time of valve closing which 33A of valve seats and the front-end | tip part 34a contact | abut. In addition, the place to which the code | symbol 41 of two places was attached is a hole for bolt insertion.

  The rubber sheet 40 may be coated on the tip 31a of the discharge valve body 31A of the discharge reed valve 31 on the surface that comes into contact with the valve seat 25A. Moreover, it is good also as a structure by which it replaces with front-end | tip parts 34a and 31a, and the rubber sheet 40 is coated by valve seat 33A, 25A. The elastic material 40 may be a synthetic resin having flexibility in addition to rubber.

  The return check valve 34 and the discharge check valve 31 may be configured by valves having a structure other than a reed valve such as an umbrella valve. The downward inclined surface 32 may be a surface inclined to the left or right, or a surface inclined downward to two or more of the front, rear, left and right, in addition to the forward or backward downward inclined surface.

1B Crankcase 3 Head cover 3A Blow-by gas outlet 19A Cover intake passage 25 Bottom wall 26 Blow-by gas passage 31 Discharge check valve 32 Down slope surface 33A Valve seat 33a Return hole 34 Return check valve 34A Valve body 34a Valve body tip 40 Elastic material B Valve train k Intake system

Claims (6)

An engine with a blow-by gas recirculation device configured to guide the blow-by gas in the crankcase from the inside of the head cover to the intake system,
The intake system has a cover intake passage provided in the head cover, and the blow-by gas passage of the head cover and the cover intake passage communicate with each other.
The bottom wall of the blow-by gas passage is provided with a return hole capable of dropping the oil captured in the blow-by gas passage,
An engine with a blow-by gas recirculation device in which a downwardly inclined surface whose height decreases toward the return hole is formed in a peripheral portion of the return hole in the bottom wall.   The blow-by gas recirculation device according to claim 1, further comprising an outflow check valve that allows oil to fall from the return hole and prevents back flow from the return hole to the blow-by gas passage side. engine.   The engine with a blow-by gas recirculation device according to claim 1 or 2, wherein a valve operating device is disposed below the return hole.   The flow check valve is constituted by a reed valve, and an elastic material is coated on a valve body tip of the reed valve or a valve body tip portion of the valve body that contacts the valve seat. The engine with a blow-by gas recirculation device according to item. The cover intake passage is provided at a blow-by gas outlet of the head cover,
The engine with a blow-by gas recirculation device according to any one of claims 1 to 4, wherein the bottom wall is a bottom wall of the blow-by gas outlet portion. The bottom wall is provided with an inflow check valve that allows inflow of blow-by gas to the blow-by gas outlet, and prevents outflow from the blow-by gas outlet,
The engine with a blow-by gas recirculation device according to claim 5, wherein a pair of the check valves for outflow are provided with the check valves for inflow interposed therebetween.

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